PORTSMOUTH — The weeping willows are painted with wisps of yellow, and the buds in the circle of star magnolia trees in Goodwin Park on Islington Street are ready to burst into bloom.

Postal carriers were spotted sporting shorts as they delivered mail by foot Monday across Portsmouth. Pedestrians sauntered in the downtown. Many picnicked outdoors at lunchtime.

People smiled.

Monday, with temperatures in the low 60s — and just a light breeze — spring appeared, at last, to make its long-awaited debut.

"Spring has sprung," said Todd Saunders of Portsmouth as he sat in one of the colorful chairs in front of Ceres Street Bakery eating soup from a yellow pottery bowl and catching up on some reading material for work.

Monday was also the home opener for the Boston Red Sox, and Saunders was eagerly anticipating a Friday night game he had tickets for at Fenway Park.

In Goodwin Park, Ellen Hirshberg of Kittery Point, Maine, had a blanket spread out on the still-brown lawn.

"This is the first time I've been able to do this this year," said Hirshberg, who has an office nearby on Islington Street. "During the summer, I like to schedule a half-hour a day to get out here for some sun."

Hirshberg said she had just called her son in California to tell him the magnolia buds in the park were "just ready to burst open."

"He wasn't sure what the big deal was, but after this winter, it is a welcome sight," she said.

Lisa Siegal and her English springer spaniel Jethro were also in the park enjoying the warm weather.

"I think spring is finally here," she said. "And, it's opening day for the Red Sox. That means spring."

Jethro was shortly joined by Winston, a 5-month-old blue Weimaraner puppy, and they cavorted joyously around their owners. Winston's owner, Mike Hanley, moved near Goodwin Park last June and Siegal excitedly told him about how beautiful the park is when the magnolias bloom.

On Woodbury Avenue, the doors were open at Portsmouth Gardens, surrounded by colorful pots of pansies, tulips and daffodils.

"People have been stopping by all morning," said employee Linda Wheeler. "As soon as they see the pansies, they get antsy and want to get out into their gardens."

One such customer was Laurie Westbrook of Portsmouth.

"This feels wonderful after such a long winter," she said. "I love this time of the year." Westbrook chose a hanging basket of pansies from one of the nursery's seven greenhouses.

Portsmouth resident Nancy Sears was also visiting the garden center.

"The weather is just beautiful today," she said. "I'm getting ready for my gardens."

But, Monday may have been just a tease, according to meteorologist Eric Sinsabaugh of the National Weather Service in Gray, Maine.

"Unfortunately, there's an unsettled week ahead," he said. "It could go into the 70s and 80s, or drop back to the 40s and 50s. I'm more inclined to think it will drop."

Sinsabaugh said people were spoiled by the mild winter and early spring last year.

"This year's weather is more typical," he said. "Winter's not wanting to leave."